Alejandro,
I found the following book very helpful:
Professional SQL Server 7.0 Programming, Rob Vieira, Wrox, ISBN 1861002319


>What is the best (least expensive) way to move into SQL server development?
>
>We are two developers. Initially only I would be "dabbling" in SQL server, but we know this is the way we want to go in the future.
>
>I am gessing it would be SQL server 2000 Developer Edition for development and MSDE for deployment at small sites.
>
>TIA,
>
>Alex